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Avian Influenza (Bird Flu)

Avian influenza (AI), commonly known as “bird flu,” is caused by an influenza type A virus.  Avian influenza viruses occur naturally in birds.  Wild bird species (such as ducks, swans and geese) can carry the viruses but usually do not get sick from them.  However, avian influenza in birds is very contagious and can make some domesticated birds (chickens, ducks, quail, pheasants, guinea fowl and turkeys) very sick or even cause death.

Avian influenza viruses do not usually infect humans, but certain strains of AI have the potential to infect people and are referred to as “zoonotic.”  If a highly pathogenic or zoonotic AI strain enters the United States, it could have serious economic and health impacts on the poultry industry and public health.

Current Status in Pennsylvania

No highly pathogenic Avian Influenza viruses have been detected in Pennsylvania since the 1983-84 outbreaks.

​​Species Affected

  • Chickens
  • Turkeys
  • Ducks
  • Quail
  • Pheasants
  • Ostriches
  • Geese
  • Swans
  • Any feathered animal


Biosecurity is most important for anyone who owns or works with poultry – whether on a commercial farm, in the wild, or at a hobby/ backyard farm.  You should take proper steps to keep HPAI from spreading.  The best way to protect your birds is to follow good biosecurity.

  • Keep your distance.
  • Keep it clean.
  • Don’t haul disease home.
  • Don’t borrow disease from your neighbor.
  • Know the warning signs of infectious bird diseases.
  • Report sick birds.

Testing Requirements

Testing requirements exist for animals moving into the commonwealth or to meet the requirements of other states to move there.  Most commercial operations are on some level of surveillance because of the necessity to maintain open markets.

Reporting Requirements

Federal and state animal health authorities have Highly Pathogenic Avian Influenza as a reportable disease which leads to restricted movement and increased surveillance to prevent further spread of the disease.

Subtypes of Avian Influenza

There are many different subtypes of influenza A viruses.  These subtypes differ and are classified based on a combination of two groups of proteins on the surface of the influenza A virus: hem agglutinin or “H” proteins, of which there are 17 (H1-H17), and neuraminidase or “N” proteins, of which there are 10 (N1-N10).  Many different combinations of “H” and “N” proteins are possible.  Each combination is considered a different subtype, and can be further broken down into different strains.  AI viruses are further classified by their pathogenicity—the ability of a particular virus strain to produce disease in domestic chickens.  Highly pathogenic avian influenza (HPAI) virus strains are extremely infectious, often fatal to domestic poultry, and can spread rapidly from flock to flock.  Low pathogenicity avian influenza (LPAI) virus strains occur naturally in wild migratory waterfowl and shorebirds without causing illness.

The avian influenza viruses that cause concern in poultry and wild birds are HPAI viruses and any virus designated as H5 or H7, because H5 and H7 viruses have the capability to convert from LPAI to HPAI.  They are considered notifiable avian influenza (NAI), and when found in a country; the World Organization of Animal Health (OIE) must be alerted.

The Asian strain of H7N9, first reported in China in spring 2013, has caused illness in people there.  We have not found this Asian strain of H7N9 in the United States, but USDA’s Animal and Plant Health Inspection Service (APHIS) is prepared to address any significant avian influenza found in our commercial poultry and wild birds.  Our focus is on preventing, looking for, and responding to the detection of the virus in birds and poultry, with an emphasis on NAI viruses.  We work collaboratively with other Government agencies, such as the Centers for Disease Control and Prevention who handle the human health impacts of avian influenza, and the Department of the Interior and state wildlife agencies who work with us on wild bird surveillance.  Since the Asian strain of H7N9 was detected only recently, we are still learning about the virus and how it behaves in both domestic and wild bird populations.  At this time, we cannot determine the risk this virus poses to North America’s birds, but from what we know about similar viruses and bird migratory patterns, the risk is presumed to be low.  We are studying the virus to better understand how it behaves so that we can most effectively look for, and if needed, respond to a detection of this strain of H7N9.


As we learn more about HPAI as it spreads across North America, PDA and its partners have developed webpages, brochures, letters, and other materials to address the needs and questions of all involved in Pennsylvania’s poultry industry.

  • HPAI Producer Response Work Plan  – Two-page document with important information for completing your USDA Flock Plan and preparing for HPAI. Please send a copy of this completed document to your integrator, if applicable, and to the department. (9/8/15).
  •  Producer checklist, resources, and contacts poster – one-page document with preparation tips, PDA resource contact information, and room to add contact information for your integrator, lender, and insurance agent. (9/8/15)
  •  HPAI Compost or Burial Options – Information for compliance with erosion and sedimentation plans when managing and disposing of dead stock. All strategies must follow a legal disposal method as defined in the PA Domestic Animal Act. (7/24/15)
  •  Model Poultry Burial E&S Plan – Narrative, sample drawing, common best management practices with illustrations, all for guidance when preparing for burial of mortalities. (7/2/15)

Other States’ HPAI Pages

Those with domesticated poultry affected by HPAI:

Pennsylvania’s Neighboring States